The father of three from Portland Row in Dublin was jailed in 2012 having shot the wrong man in a gun attack at Dooradoyle in Limerick in November 2008.
Barry Doyle's lawyers raised 27 grounds of appeal, many centred on his confession while in garda custody that he'd shot Shane Geoghegan.
It was submitted that gardaí induced him to make admissions by promising to release his former partner Victoria Gunnery who'd been arrested for withholding information.
The Court of Appeal has found there was no threat or inducement and they laid weight on the fact that his confession came after a consultation with his solicitor.
They've found that Barry Doyle knew what he was doing.
He's not the only person serving life for the murder in 2013 the Special Criminal Court convicted Limerick gang figure John Dundon on accomplice evidence that he'd ordered Barry Doyle to carry out the shooting.
Shane Geoghegan was not the intended target he was gunned down metres from his home.
